He uses salami slicing to get what he wants.
salami slicing
idiomThe achievement of a large change by incrementally asking for small concessions.
Origin
disputed originFrom the way a deli will slice salami or similar meat in small slices in order to fill a sandwich at lowest cost.
The manager used salami slicing to slowly change the team's schedule without causing a major protest.
By employing a strategy of salami slicing, the committee gradually implemented the controversial policy through a series of minor, seemingly harmless amendments.